Details
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Improvement
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Status: Open
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Major
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Resolution: Unresolved
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1.14.4
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None
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flink-kubernetes-operator 1.0.0
Flink 1.14-java11
Kubernetes v1.19.5
Istio 1.7.6
Description
Hello,
We are launching Flink deployments using the Flink Kubernetes Operator on a Kubernetes cluster with Istio and mTLS enabled.
We found that the TaskManager is unable to communicate with the JobManager on the jobmanager-rpc port:
2022-06-15 15:25:40,508 WARN akka.remote.ReliableDeliverySupervisor [] - Association with remote system akka.tcp://[flink@amf-events-to-inference-and-central.nwdaf-edge
has failed, address is now gated for [50] ms. Reason: [Association failed with akka.tcp://[flink@amf-events-to-inference-and-central.nwdaf-edge] Caused by: [The remote system explicitly disassociated (reason unknown).]
The reason for the issue is that the JobManager service port definitions are not following the Istio guidelines https://istio.io/latest/docs/ops/configuration/traffic-management/protocol-selection/ (see example below).
There was also an email discussion around this topic in the users mailing group under the subject "Flink Kubernetes Operator with K8S + Istio + mTLS - port definitions".
With the help of the community, we were able to work around the issue but it was very hard and forced us to skip Istio proxy which is not ideal.
We would like you to consider changing the default port definitions, either
- Rename the ports – I understand it is Istio specific guideline but maybe it is better to at least be aligned with one (popular) vendor guideline instead of none at all.
- Add the “appProtocol” property[1] that is not specific to any vendor but requires Kubernetes >= 1.19 where it was introduced as beta and moved to stable in >= 1.20. The option to add appProtocol property was added only in https://github.com/fabric8io/kubernetes-client/releases/tag/v5.10.0 with #3570.
- Or allow a way to override the defaults.
https://kubernetes.io/docs/concepts/services-networking/_print/#application-protocol
# k get service inference-results-to-analytics-engine -o yaml
apiVersion: v1
kind: Service
...
spec:
clusterIP: None
ports:
- name: jobmanager-rpc # should start with “tcp-“ or add "appProtocol" property
port: 6123
protocol: TCP
targetPort: 6123
- name: blobserver # should start with "tcp-" or add "appProtocol" property
port: 6124
protocol: TCP
targetPort: 6124
...
Attachments
Issue Links
- duplicates
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FLINK-31775 High-Availability not supported in kubernetes when istio enabled
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- Closed
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- links to